A program has been initiated to identify dietary constituents effecting the cataract incidence in rats with heredity retinal dystrophy. Thus far, preliminary studies have shown that almost 100% of the rats fed a natural ingredient diet develop cataracts that may be detected as early as seven weeks of age whereas, practically no cataracts have been detected in rats fed a purified diet. A series of factural studies are being used to identify the factor in the natural ingredient diet that apparently stimulates the development of cataracts in this particular strain.